This invention relates to methods of preparing sodium-hydrogen exchanger type 1 (NHE-1) inhibitors, intermediates of NHE-1 inhibitors and a new almost colorless form of the NHE-1 inhibitor, N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine.
Sodium-hydrogen exchanger type 1 (NHE-1) inhibitors of formula Ixe2x80x2
are useful for the prevention and treatment of myocardial ischemic injury. Myocardial ischemic injury can occur in out-patient as well as in perioperative settings and can lead to the development of sudden death, myocardial infarction or congestive heart failure. It is anticipated that therapies using the NHE-1 inhibitors of formula Ixe2x80x2 will be life-saving and reduce hospitalizations, enhance quality of life and reduce overall health care costs of high risk patients.
Commonly assigned WO 99/43663A1, the disclosure of which is hereby incorporated by reference, discloses a variety of NHE-1 inhibitors including the NHE-1 inhibitors of the present invention.
J. Med. Chem. 1997, 40, 2017-2034 xe2x80x9c(2-Methyl-5-(methylsulfonyl)benzoyl)guanidine Na+/H+ Antiporter Inhibitorsxe2x80x9d and Arzneim.-Forsch. (Drug Res.) 25, Nr. 10 (1975) xe2x80x9cSubstituted Phenylacetylguanidines: a New Class of Antihypertensive Agentsxe2x80x9d disclose synthesizing acyl guanidine via coupling of an ester and guanidine, in addition to an acid chloride and guanidine wherein the substrates are aromatic monocyclic structures.
J. Heterocyclic Chem., 24, 1669 (1987) xe2x80x9cReaction of 2-Dimethylaminomethylene-1,3-diones with Dinucleophiles. VI. Synthesis of Ethyl or Methyl 1,5-Disubsittuted 1H-Pyrazole-4-carboxylatesxe2x80x9d discloses the preparation of esters of 5-substituted 1-phenyl-1H-pyrazole-4-carboxylic acids.
Ferlin, et al., II Famraco, 44:12, pp 1141-1156 (1989) discloses a method of synthesizing 5-hydrazinoquinoline by reacting quinolin-5-ylamine with stannous chloride and sodium nitrite.
When N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine, an NHE-1 inhibitor of formula Ixe2x80x2, is prepared by the previously known processes, colored impurities are produced. Aqueous solutions of N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine made by the previously known processes have a distinct yellow color. The impurities responsible for such coloration have not been identified.
From a commercial and regulatory point of view, discoloration of pharmaceutical products containing N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine is undesirable. In the case of pharmaceutical products that are administered to patients, especially products that are injected in patients"" bodies, it is advantageous to have products that are almost colorless and whose active ingredient is in as pure a form as possible.
This invention relates to a novel process using ascorbic acid to prepare NHE-1 inhibitors of formula Ixe2x80x2
wherein R1 is methylsulfonyl or hydrogen, R2 is hydrogen or a halogen, R3 is hydrogen, R4 is hydrogen or a halogen, or R3 and R4 form, together with the carbon atoms to which they are attached, a six member fully unsaturated ring having one hetero atom that is nitrogen.
It has been discovered that when the NHE-1 inhibitor, N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine, is prepared by the ascorbic acid process of this invention, the final product has fewer colored impurities and is obtained in higher yield than that made by previous processes. It has also been discovered that by using citric acid in the preparation of N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine, these colored impurities are further reduced.
One aspect of this invention is methods of preparing compounds of formula VIxe2x80x2
wherein R1 is methylsulfonyl or hydrogen, R2 is hydrogen or a halogen, R3 is hydrogen, R4 is hydrogen or a halogen, or R3 and R4 form, together with the carbon atoms to which they are attached, a six member fully unsaturated ring having one hetero atom that is nitrogen, comprising reducing, with ascorbic acid, compounds of formula IIxe2x80x2
wherein X is chloride, bromide, iodide, xc2xd(SO4)2xe2x88x92 or tetrafluoroborate and R1, R2, R3 and R4 are as defined for formula VIxe2x80x2 above.
Another aspect of the invention is methods of preparing compounds of formula VIxe2x80x2, comprising combining compounds formula IIxe2x80x2, with ascorbic acid to form compounds of formula Vxe2x80x2
wherein R1, R2, R3 and R4 are as defined for formula VIxe2x80x2 above, and heating the compound of formula Vxe2x80x2 to a temperature above about 50xc2x0 C. to form compounds of formula VIxe2x80x2.
A further aspect of the invention is methods of preparing compounds of formula Ixe2x80x2
wherein R1, R2, R3 and R4 are as defined for formula VIxe2x80x2 above, comprising combining the compound of formula VIxe2x80x2 made by a method of this invention, with xcex1-[(dimethylamino)methylene]-xcex2-oxo-cyclopropanepropanoic acid, (xcex1Z)-methylester to form compounds of formula VIIIxe2x80x2
wherein R1, R2, R3 and R4 are as defined for formula VIxe2x80x2 above, and coupling said formula VIIIxe2x80x2 compound with guanidine to form the compound of formula Ixe2x80x2.
A still further aspect of this invention is compounds of formula Vxe2x80x2
wherein R1, R2, R3 and R4 are as defined for formula VIxe2x80x2 above.
Another aspect of this invention is compounds of formula IVxe2x80x2
wherein R1, R2, R3 and R4 are as defined for formula VIxe2x80x2 above.
A further aspect of this invention is methods of preparing 5-hydrazinoquinoline comprising reduction of a diazonium salt of 5-aminoquinoline with ascorbic acid.
An additional aspect of this invention is methods of preparing 5-hydrazinoquinoline comprising combining a diazonium salt of 5-aminoquinoline with ascorbic acid to form [2-(5-quinolinyl)hydrazide]-ethanedioic acid and heating said [2-(5-quinolinyl)hydrazide]-ethanedioic acid to a temperature above about 35xc2x0 C., preferably above about 50xc2x0 C. and most preferably above about 80xc2x0 C., in an aqueous solution containing a hydrolyzing agent, preferably hydrochloric acid.
Another aspect of this invention is methods of preparing [2-(5-quinolinyl)hydrazide]-ethanedioic acid comprising combining a diazonium salt of 5-aminoquinoline with ascorbic acid to form a reaction mixture and maintaining said reaction mixture at a temperature below about 25xc2x0 C.
A further aspect of this invention is the compound [2-(5-quinolinyl)hydrazide]-ethanedioic acid.
A still further aspect of this invention is the compound of formula IV 
An additional aspect of this invention is methods of preparing N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine comprising:
combining 5-hydrazinoquinoline made by a method of this invention with xcex1-[(dimethylamino)methylene]-xcex2-oxo-cyclopropanepropanoic acid, (xcex1Z)-methyl ester to form 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester; and
coupling said 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester with guanidine to form N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine.
Another aspect of this invention is methods of preparing N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine comprising:
combining 5-hydrazinoquinoline made by a method of this invention with xcex1-[(dimethylamino)methylene]-xcex2-oxo-cyclopropanepropanoic acid, (xcex1Z)-methyl ester to form 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester;
hydrolyzing said 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester with an inorganic base to form 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid; and
coupling said 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid with guanidine to form N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine.
A further aspect of this invention is methods of preparing N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine comprising:
treating 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester with citric acid to form purified 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester; and
coupling said purified 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester with guanidine to form N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine.
Another aspect of this invention is methods of preparing N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine comprising:
treating 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester with citric acid to form purified 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester;
hydrolyzing said purified 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester with an inorganic base to form 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid; and
coupling said 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid with guanidine to form N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine.
A still further aspect of this invention is methods of preparing N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine comprising:
treating 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester dissolved in an inert solvent, preferably ethyl acetate, with citric acid dissolved in an aqueous solution to form purified 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester, wherein said 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester is preferably prepared by combining 5-hydrazinoquinoline made by a method of this invention with xcex1-[(dimethylamino)methylene]-xcex2-oxo-cyclopropanepropanoic acid, (xcex1Z)-methyl ester;
hydrolzying said purified 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester with an inorganic base, preferably selected from sodium hydroxide, lithium hydroxide and potassium hydroxide and preferably wherein the base is dissolved in a solvent selected from water, methanol and tetrahydrofuran, to form 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid;
treating said 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid with a coupling agent to form an activated compound that is reactive with guanidine;
coupling the activated compound with guanidine to form N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine.
An additional aspect of this invention is methods of preparing 2-chloro-4-methanesulfonyl-2-phenylhydrazine comprising reduction of a diazonium salt of 2-chloro-4-methanesulfonyl-phenylamine with ascorbic acid.
Another aspect of this invention is methods of preparing 2-chloro-4-methanesulfonyl-2-phenylhydrazine comprising:
combining a diazonium salt of 2-chloro-4-methanesulfonyl-phenylamine with ascorbic acid to form mono [2-[2-chloro-4-(methyl sulfonyl)phenyl]hydrazide]ethanedioic acid; and
heating said [2-[2-chloro-4-(methyl sulfonyl)phenyl]hydrazide]ethanedioic acid to a temperature above about 35xc2x0 C., preferably above about 50xc2x0 C. and most preferably above about 80xc2x0 C., in an aqueous solution containing a hydrolyzing agent, preferably hydrochloric acid, to form 2-chloro-4-methanesulfonyl-2-phenylhydrazine.
A further aspect of this invention is methods of preparing [2-[2-chloro-4-(methyl sulfonyl)phenyl]hydrazide]ethanedioic acid comprising combining a diazonium salt of 2-chloro-4-methanesulfonyl-phenylamine with ascorbic acid to form a reaction mixture and maintaining said reaction mixture at a temperature below about 25xc2x0 C.
A still further aspect of this invention is methods of preparing N-{5-cyclopropyl-1-(2-chloro-4-methanesulfonylphenyl)-1H-pyrazole-4-carbonyl}-guanidine comprising:
combining 2-chloro-4-methanesulfonyl-2-phenylhydrazine made by a method of this invention with xcex1-[(dimethylamino)methylene]-xcex2-oxo-cyclopropanepropanoic acid, (xcex1Z)-methyl ester to form 5-cyclopropyl-1-(2-chloro-4-methanesulfonylphenyl)-1H-pyrazole-4-carboxylic acid methyl ester; and
coupling said 5-cyclopropyl-1-(2-chloro-4-methanesulfonylphenyl)-1H-pyrazole-4-carboxylic acid methyl ester with guanidine to form N-{5-cyclopropyl-1-(2-chloro-4-methanesulfonylphenyl)-1H-pyrazole-4-carbonyl}-guanidine.
An additional aspect of this invention is methods of preparing N-{5-cyclopropyl-1-(2-chloro-4-methanesulfonylphenyl)-1H-pyrazole-4-carbonyl}-guanidine comprising:
combining 2-chloro-4-methanesulfonyl-2-phenylhydrazine made by a method of this invention with xcex1-[(dimethylamino)methylene]-xcex2-oxo-cyclopropanepropanoic acid, (xcex1Z)-methyl ester to form 5-cyclopropyl-1-(2-chloro-4-methanesulfonylphenyl)-1H-pyrazole-4-carboxylic acid methyl ester;
hydrolyzing said 5-cyclopropyl-1-(2-chloro-4-methanesulfonylphenyl)-1H-pyrazole-4-carboxylic acid methyl ester with an inorganic base to form 5-cyclopropyl-1-(2-chloro-4-methanesulfonylphenyl)-1H-pyrazole-4-carboxylic acid; and
coupling said 5-cyclopropyl-1-(2-chloro-4-methanesulfonylphenyl)-1H-pyrazole-4-carboxylic acid with guanidine to form N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine.
Another aspect of this invention is N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine and pharmaceutically acceptable salts thereof, preferably N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine monomesylate, having a light absorption at 450 nanometers in a 1% water solution at 25xc2x0 C. of less than about 0.02 and preferably less than about 0.01.
Another aspect of this invention is a pharmaceutical composition comprising N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine and pharmaceutically acceptable salts thereof, preferably N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine monomesylate, having a light absorption at 450 nanometers in a 1% water solution at 25xc2x0 C. of less than about 0.02 and preferably less than about 0.01 and a pharmaceutically acceptable vehicle, diluent or carrier.
A still further aspect of this invention is a method of reducing tissue damage resulting from ischemia or hypoxia comprising administering to a mammal in need of such treatment a therapeutically effective amount of N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine and pharmaceutically acceptable salts thereof, preferably N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine monomesylate, having less than a light absorption at 450 nanometers of less than about 0.02 and preferably less than about 0.01 in a 1% water solution at 25xc2x0 C., or a pharmaceutically acceptable composition comprising said compound.
In a preferred embodiment of the method aspects of this invention said ascorbic acid is L-ascorbic acid.
The term xe2x80x9cinert solventxe2x80x9d refers to a solvent system in which the components do not interact with starting materials, reagents, intermediates or products in a manner which adversely affects the yield of the desired product.
The term xe2x80x9clight absorptionxe2x80x9d refers to the absorption of light in a solution as calculated by the formula, A=log10(I0/I), wherein xe2x80x9cI0xe2x80x9d is incident light and xe2x80x9cIxe2x80x9d is transmitted light. This formula is derived from the equation, log10(I0/I)=xcex5xc2x7Ixc2x7c, wherein xcex5 is the molar extinction coefficient of the solution in cm2/mole, I is the path length of the absorbing solution in centimeters and c is the concentration in moles/liter.
The expression xe2x80x9cpharmaceutically-acceptable saltxe2x80x9d refers to nontoxic anionic salts containing anions such as (but not limited to) chloride, bromide, iodide, sulfate, bisulfate, phosphate, acetate, maleate, fumarate, oxalate, lactate, tartrate, citrate, gluconate, methanesulfonate and 4-toluene-sulfonate. Where more than one basic moiety exists, the expression includes multiple salts (e.g., di-salt). The expression also refers to nontoxic cationic salts such as (but not limited to) sodium, potassium, calcium, magnesium, ammonium or protonated benzathine (N,Nxe2x80x2-dibenzylethylenediamine), choline, ethanolamine, diethanolamine, ethylenediamine, meglamine (N-methyl-glucamine), benethamine (N-benzylphenethylamine), piperazine or tromethamine (2-amino-2-hydroxymethyl-1,3-propanediol).
The term xe2x80x9cpurifiedxe2x80x9d when used in connection with 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester means 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester that has been treated so as to reduce the presence of colored impurities.
Those skilled in the art will recognize that certain compounds of this invention will contain one or more atoms that may be in a particular stereochemical or geometric configuration, giving rise to stereoisomers and configurational isomers. All such isomers and mixtures thereof are included in this invention.
Reaction Scheme A illustrates the process of preparing compounds of formula VIxe2x80x2. Scheme B illustrates the process of preparing compounds of formula Ixe2x80x2 using compounds of formula VIxe2x80x2 from Scheme A. This process is used to make NHE-1 inhibitors, including N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine. 
According to Scheme A, a diazonium salt of formula IIxe2x80x2 is combined with L-ascorbic acid (formula III) to form the lactone intermediate compounds of formula IVxe2x80x2 as a transient intermediate, which decomposes to the formula Vxe2x80x2 oxalic acid intermediate. At elevated reaction temperatures, above about 35xc2x0 C. and preferably above about 50xc2x0 C. and most preferably above about 80xc2x0 C., the formula IVxe2x80x2 compounds convert to the formula VIxe2x80x2 compound as a one-pot reaction. At lower temperatures, the formula Vxe2x80x2 oxalic acid intermediate compounds are not converted to the formula VIxe2x80x2 compound. The formula Vxe2x80x2 oxalic compound may be converted to the formula VIxe2x80x2 hydrazino compound as the hydrochloride by hydrolysis with concentrated hydrochloric acid.
The lactone intermediates of formula IVxe2x80x2 are unstable and decompose under the reaction conditions into the oxalic acid derivative. However, when the diazonium salt of formula IIxe2x80x2 derived from 2,5-dichlorophenylaniline is used to make the formula IIxe2x80x2 diazonium salt, it is possible to isolate the lactone intermediate. NMR analysis of this compound gives results that are consistent with a lactone structure.
Scheme B illustrates the process of preparing the compound of formula Ixe2x80x2. The formula VIxe2x80x2 hydrazino compound is combined with the formula VII compound in an inert solvent such as ethyl acetate at a temperature of about 20xc2x0 C. for about one hour followed by heating to a temperature of about 75xc2x0 C. for about five hours to form the formula VIIIxe2x80x2 pyrazole compound.
The formula VII compound may be prepared by combining methyl-3-cyclopropyl-3-oxopropanoate in ethyl acetate with N,N-dimethylformamide dimethylacetal at about 65xc2x0 C. to about 75xc2x0 C. for about 4 hours.
The formula VIIIxe2x80x2 pyrazole is hydrolyzed with a base such as sodium hydroxide, lithium hydroxide or potassium hydroxide in a solvent such as water and/or methanol and/or THF conveniently at ambient temperature or at elevated temperature (e.g., reflux) for about one hour to about five hours to prepare the formula IXxe2x80x2 acid.
The formula IXxe2x80x2 acid is activated with a coupling agent such as thionyl chloride at a temperature of about 60xc2x0 C. to about 90xc2x0 C. for about 13 hours to form the formula Xxe2x80x2 acid chloride. Other suitable coupling agents may be used. A suitable coupling agent is one which transforms the carboxylic acid into a reactive species which forms an acyl guanidine on reaction with guanidine. The coupling agent can convert the carboxylic acid to an activated intermediate which is isolated and/or formed in a first step and allowed to react with guanidine in a second step. Examples of such coupling agents and activated intermediates are thionyl chloride or oxalyl chloride to form the acid chloride, cyanuric flouride to form an acid flouride or an alkyl chloroformate such as isobutyl or isopropenyl chloroformate or propanephosphonic anhydride to form a mixed anhydride of the carboxylic acid, or carbonyidimidazole to form an acylimidazole. Alternatively, the coupling agent may be a reagent which effects coupling in a one pot process. Exemplary coupling reagents are 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride-hydroxybenzotriazole (EDC/HOBT), dicyclohexylcarbodiimide/hydroxybenzotriazole (DCC/HOBT),2-ethoxy-1-ethoxycarbonyl-,2dihydroquinoline (EEDQ) and diethylphosphorylcyanide. The coupling is performed in an inert solvent, preferably an aprotic solvent, in the presence of excess guanidine. Exemplary solvents include acetonitrile, dichloromethane, dimethylformamide and chloroform or mixtures thereof. Use of these coupling agents and appropriate selection of solvents and temperatures are known to those skilled in the art or can be readily determined from the literature in light of this disclosure. These and other exemplary conditions useful for coupling carboxylic acids are described in Houben-Weyl, Vol XV, part II, E. Wunsch, Ed., G. Theime Verlag, 1974, Stuttgart; M. Bodansky, Principles of Peptide Synthesis, Springer-Verlag, Berlin 1984; and The Peptides, Analysis, Synthesis and Biology (ed. E. Gross and J. Meienhofer), vols 1-5 (Academic Press, NY 1979-1983).
The formula X compound is coupled with guanidine to form the NHE-1 inhibitor of formula Ixe2x80x2 by combining the formula Xxe2x80x2 compound with guanidine hydrochloride and an inorganic base such as sodium hydroxide, lithium hydroxide or potassium hydroxide in a solvent which is preferably selected from water, methanol and tetrahydrofuran.
In a preferred embodiment of the reactions of Scheme A and Scheme B, the formula IIxe2x80x2 compound is a diazonium salt of 5-aminoquinoline. The diazonium salt of 5-aminoquinoline is combined with ascorbic acid to form the compound of formula VIxe2x80x2 that is 5-hydrazinoquinoline. The formula VIIIxe2x80x2 pyrazole formed is 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester. Prior to the coupling step with guanidine, 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester is preferably treated with citric acid to remove red impurities. In this treatment, the solvent solution containing 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester is combined with an aqueous solution of citric acid to form a darker red aqueous layer and a red organic layer. The aqueous layer is discarded.
The citric acid purified 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid methyl ester is hydrolyzed with a base such as sodium hydroxide in water to form 5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid, analogous to the formula IXxe2x80x2 acid. 5-Cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carboxylic acid is then activated with a coupling agent such as thionyl chloride to form the chloride compound, analogous to the formula Xxe2x80x2 compound. The chloride activated compound is then coupled with guanidine to form the NHE-1 inhibitor, N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine.
N-(5-Cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine prepared by a method of this invention may be converted to pharmaceutically acceptable salts. For example N-(5-cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine may be converted to its mesylate salt by combining the compound with methanesulfonic acid, preferably in a polar aprotic solvent at a temperature of about 40xc2x0 C. to about 80xc2x0 C. The polar aprotic solvent is preferably a mixture of acetone and 1-methyl-2-pyrrolidonone. Conversion to other pharmaceutically acceptable salts may be performed by processes known in the art.
N-(5-Cyclopropyl-1-quinolin-5-yl-1H-pyrazole-4-carbonyl)-guanidine monomesylate, when prepared by the chemical processes and methods outlined above, gives rise to 1% aqueous solutions with very low blue light absorption. At 450 nm the light absorption of a 1% solution is in the range 0.007-0.005. Previous procedures gave rise to distinctly yellow solutions with absorption levels in the range 0.027-0.025. Light absorption is calculated according to the formula, A=log10(I0/I), wherein xe2x80x9cI0xe2x80x9d is incident light and xe2x80x9cIxe2x80x9d is transmitted light.
In another preferred embodiment, the formula IIxe2x80x2 compound is a diazonium salt of 2-chloro-4-methanesulfonyl-phenylamine. The diazonium salt is combined with ascorbic acid to form the compound of formula VIxe2x80x2 that is 2-chloro-4-methanesulfonyl-2-phenylhydrazine. The formula VIIIxe2x80x2 pyrazole formed is 5-cyclopropyl-1-(2-chloro-4-methanesulfonylphenyl)-1H-pyrazole-4-carboxylic acid methyl ester.
5-Cyclopropyl-1-(2-chloro-4-methanesulfonylphenyl)-1H-pyrazole-4-carboxylic acid methyl ester is hydrolyzed with a base such as sodium hydroxide in water to form 5-cyclopropyl-1-(2-chloro-4-methanesulfonylphenyl)-1H-pyrazole-4-carboxylic acid, analogous to the formula IXxe2x80x2 acid. The carboxylic acid pyrazole is then activated with coupling agent such as thionyl chloride to form the activated compound, analogous to the formula Xxe2x80x2 compound. The activated compound is then coupled with guanidine to form the NHE-1 inhibitor, N-{5-cyclopropyl-1-(2-chloro-4-methanesulfonylphenyl)-1H-pyrazole-4-carbonyl}-guanidine.
An alternative, which is not shown in Scheme B, is the direct conversion of the Formula VIIxe2x80x2 pyrazole to the NHE-1 inhibitor of Formula Ixe2x80x2 by several methods. For example, the Formula VIIIxe2x80x2 pyrazole can be heated in the presence of excess guanidine, in a polar protic solvent for example, methanol or isopropanol, at a suitable temperature, conveniently at reflux for about one to about seventy-two hours. This transformation may also be performed by repeatedly removing the solvent, for example, removing ethanol or toluene, about four times from a mixture of the Formula VIIIxe2x80x2 pyrazole and excess guanidine at a pressure of about one to about 100 mmHg and at a temperature of about 25xc2x0 C. to about 95xc2x0 C. This reaction may also be performed in the absence of solvent by heating the mixture of the formula VIIIxe2x80x2 pyrazole and excess guanidine at a temperature of about 100xc2x0 C. to about 180xc2x0 C., optionally at a pressure of about 1 to about 100 mmHg for about five minutes to about eight hours.
The starting material and reagents for the above described compounds are readily available or can be easily synthesized by those skilled in the art using conventional methods of organic synthesis.
Administration of the compounds prepared by a method of this invention can be via any method which delivers a compound of this invention preferentially to the desired tissue (e.g., liver and/or cardiac tissues). These methods include oral routes, parenteral, intraduodenal routes, etc. Generally, the compounds of the present invention are administered in single (e.g., once daily) or multiple doses or via constant infusion.
The compounds prepared by a method of this invention are useful, for example, in reducing or minimizing damage effected directly to any tissue that may be susceptible to ischemia/reperfusion injury (e.g., heart, brain, lung, kidney, liver, gut, skeletal muscle, retina) as the result of an ischemic event (e.g., myocardial infarction). The active compound is therefore usefully employed prophylactically to prevent, i.e. (prospectively or prophylactically) to blunt or stem, tissue damage (e.g., myocardial tissue) in patients who are at risk for ischemia (e.g., myocardial ischemia).
Generally, the compounds prepared by a method of this invention are administered orally, or parenterally (e.g., intravenous, intramuscular, subcutaneous or intramedullary). Topical administration may also be indicated, for example, where the patient is suffering from gastrointestinal disorders or whenever the medication is best applied to the surface of a tissue or organ as determined by the attending physician.
The amount and timing of compounds administered will, of course, be dependent on the subject being treated, on the severity of the affliction, on the manner of administration and on the judgement of the prescribing physician. Thus, because of patient to patient variability, the dosages given below are a guideline and the physician may titrate doses of the drug to achieve the treatment that the physician considers appropriate for the patient. In considering the degree of treatment desired, the physician must balance a variety of factors such as age of the patient, presence of preexisting disease, as well as presence of other diseases (e.g., cardiovascular disease).
For example, in one mode of administration, the compounds prepared by a method of this invention may be administered just prior to surgery (e.g., within twenty-four hours before surgery for example cardiac surgery) during or subsequent to surgery (e.g., within twenty-four hours after surgery) where there is risk of myocardial ischemia. The compounds may also be administered in a chronic daily mode.
Amounts of the compounds prepared by a method of this invention are used that are effective for ischemic protection. A preferred dosage is about 0.001 to 100 mg/kg/day of the compounds. An especially preferred dosage is about 0.01 to 50 mg/kg/day of the compounds.
The compounds of the present invention are generally administered in the form of a pharmaceutical composition comprising at least one of the compounds of this invention together with a pharmaceutically acceptable vehicle, carrier or diluent. Thus, the compounds of this invention can be administered individually or together in any conventional oral, parenteral, rectal or transdermal dosage form.
For oral administration a pharmaceutical composition can take the form of solutions, suspensions, tablets, pills, capsules, powders, and the like. Tablets containing various excipients such as sodium citrate, calcium carbonate and calcium phosphate are employed along with various disintegrants such as starch and preferably potato or tapioca starch and certain complex silicates, together with binding agents such as polyvinylpyrrolidone, sucrose, gelatin and acacia. Additionally, lubricating agents such as magnesium stearate, sodium lauryl sulfate and talc are often very useful for tabletting purposes. Solid compositions of a similar type are also employed as fillers in soft and hard-filled gelatin capsules; preferred materials in this connection also include lactose or milk sugar as well as high molecular weight polyethylene glycols. When aqueous suspensions and/or elixirs are desired for oral administration, the compounds of this invention can be combined with various sweetening agents, flavoring agents, coloring agents, emulsifying agents and/or suspending agents, as well as such diluents as water, ethanol, propylene glycol, glycerin and various like combinations thereof.
For purposes of parenteral administration, solutions, for example, in sesame or peanut oil or in aqueous propylene glycol can be employed, as well as sterile aqueous solutions of the corresponding water-soluble salts. Such aqueous solutions may be suitably buffered, if necessary, and the liquid diluent first rendered isotonic with sufficient saline or glucose. These aqueous solutions are especially suitable for intravenous, intramuscular, subcutaneous and intraperitoneal injection purposes. In this connection, the sterile aqueous media employed are all readily obtainable by standard techniques well-known to those skilled in the art.
For purposes of transdermal (e.g.,topical) administration, dilute sterile, aqueous or partially aqueous solutions (usually in about 0.1% to 5% concentration), otherwise similar to the above parenteral solutions, are prepared.
Methods of preparing various pharmaceutical compositions with a certain amount of active ingredient are known, or will be apparent in light of this disclosure, to those skilled in this art. For examples of methods of preparing pharmaceutical compositions, see Remington: The Science and Practice of Pharmacy, Mack Publishing Company, Easton, Pa., 19th Edition 1995.
Pharmaceutical compositions according to the invention may contain for example 0.0001%-95% of the compounds prepared by a method of this invention. In any event, the composition or formulation to be administered will contain a quantity of the compound(s) prepared according to the invention in an amount effective to treat the disease/condition of the subject being treated.
NMR spectra were recorded on a Varian XL-300 (Varian Co., Palo Alto, Calif.), a Bruker AM-300 spectrometer (Bruker Co., Billerica, Mass.) or a Varian Unity 400 at about 23xc2x0 C. at 300 or 400 MHz for proton. Chemical shifts are expressed in parts per million downfield from trimethylsilane. The peak shapes are denoted as follows: s=singlet; d=doublet; t=triplet, q=quartet; m=multiplet; bs=broad singlet.